CRA recently released a letter which discusses whether an organization approved for registration as a qualified donee (as a public body performing a function of government) by the Charities Directorate requires a separate ruling to claim tax exemption under 149 (1)(c). CRA determined that a separate ruling (from the Income Tax Rulings Directorate) is not required, unless circumstances change and the status of the qualified donee will need to be reviewed, at which time a separate ruling may be requested. 

Here is a copy of the CRA letter.